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351.
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353.
Role of marine biology in glacial-interglacial CO2 cycles 总被引:1,自引:0,他引:1
It has been hypothesized that changes in the marine biological pump caused a major portion of the glacial reduction of atmospheric carbon dioxide by 80 to 100 parts per million through increased iron fertilization of marine plankton, increased ocean nutrient content or utilization, or shifts in dominant plankton types. We analyze sedimentary records of marine productivity at the peak and the middle of the last glacial cycle and show that neither changes in nutrient utilization in the Southern Ocean nor shifts in plankton dominance explain the CO2 drawdown. Iron fertilization and associated mechanisms can be responsible for no more than half the observed drawdown. 相似文献
354.
世界卫生组织根据农药对人的急性毒性将农药分成5类,其类别从“有急性毒性”到“正常使用时没有急性毒性”,一些农药被归之为持久性有机污染物(POP),致癌,致畸或内分泌干扰物。分析食品和环境中的分布以保证食品安全,是一项经常工作。目前,很多分析方法仅针对一部分可能存在的化合物,然而无论是食品还是环境样品,由于其中一些天然产物能够被一起提取出来,致使分析工作变得复杂起来。因此,在分析之前需要进行若干样品净化步骤,但即便如此,在残余基质存在的情况下检测痕量的污染物也很困难。 相似文献
355.
Christopher P.Sandy 《农业质量标准》2006,(6):32-34
对农药残留的质谱分析一般需要找到目标离子,并核对辅助定量离子的比例。有时要从高度复杂的基质背景中确证目标化合物是非常困难的,因为基质影响了目标化合物的离子比例,或者增加的离子使图谱变得更复杂了。要使结果更明确,经常需要扣除背景和进行手工积分。所以,从复杂基质中 相似文献
356.
Terry L. Blanchard Steven P. Brinsko Charles C. Love Dickey D. Vest Christopher B. Berezowski Konnie M. Wendt Kelly Stich Dickson D. Varner 《Journal of Equine Veterinary Science》2012,32(1):5-11
The objective of this case study was to investigate whether semen centrifugation and low-dose insemination techniques would improve fertility of an aged subfertile Quarter Horse stallion with low sperm concentration, motility, and morphology in ejaculates. Forty-five mares were bred by one of five treatments (n = 9 per group) using the entire ejaculate as follows: (1) Group Body: body insemination with ejaculate diluted 1:1 in TAMU extender; (2) Group Body-Cent: body insemination after centrifugation and re-suspension of sperm pellet to 1 mL in TAMU extender; (3) Group Horn-Cent: deep horn insemination after centrifugation and re-suspension of sperm pellet to 1 mL in TAMU extender; (4) Group Cent-Hys: hysteroscopic insemination onto the uterotubal papilla after centrifugation and re-suspension of sperm pellet to 200 μL in Kenney-Modified Tyrode’s extender; and (5) Group Dens-Hys: hysteroscopic insemination onto the uterotubal papilla after discontinuous density gradient centrifugation and re-suspension of the sperm pellet in 200-μL Kenney-Modified Tyrode’s extender. Pregnancy rates did not differ among treatment groups (P = .77). Semen centrifugation for low dose insemination did not appear to improve fertility of this subfertile stallion, despite use of entire ejaculates for each individual insemination dose. 相似文献
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358.
This randomised, blinded, cross-over study investigated the ease of oral transmucosal administration of two formulations of buprenorphine using glucose as a control in 12 cats. The cats received three treatments: buprenorphine multi-dose, buprenorphine and the equivalent volume of glucose 5%. Ease of treatment administration, observation of swallowing, changes in pupil size, sedation, salivation, vomiting, behaviour and food intake were assessed. The data were analysed using MLwiN and multi-level modelling. Ease of administration of buprenorphine multi-dose was statistically different from glucose (P <0.001), and the administration of all treatments became easier over the study periods. Swallowing was not statistically different between groups (P >0.05). Mydriasis was evident after the administration of both formulations of buprenorphine. Sedation, salivation, vomiting, behavioural changes or in-appetence were not observed after any treatment. Cats tolerated oral transmucosal administration of glucose better than buprenorphine multi-dose, while buprenorphine administration was tolerated as well as glucose. 相似文献
359.
Whittaker AG Love S Parkin TD Duz M Cathcart M Hughes KJ 《Veterinary journal (London, England : 1997)》2012,191(2):208-212
The pH measurement of exhaled breath condensate (EBC) may provide a non-invasive method of assessing the lower airways of horses but the methodology used may influence findings. The aim of this study was to investigate the effect of two sampling devices and three methods of condensation surface cooling (ethanol slush, -100°C; dry ice, -75°C; water ice, 0°C) on EBC pH. Each method was tested 30 times using six healthy ponies. Sample pH was determined before and after de-aeration with argon for 10 min. Sampler design was found to significantly affect pH. Samples collected as a liquid had a significantly higher pH than samples frozen during collection (P<0.05). De-aeration resulted in significantly higher pH (P<0.05) with less variation. This study has shown that device design and condensation surface temperature will influence EBC pH, which will prevent a direct comparison of results when different methodologies are used. 相似文献
360.
Bortolami E Love EJ Harcourt-Brown TR Higgs P Robinson K 《Veterinary anaesthesia and analgesia》2012,39(4):446-447